Relay Logic Symbols: Ladder Logic borrows symbols from traditional relay logic, making it easy for engineers familiar with relay-based control systems to transition to PLC programming.

Relay instructions. PLCs perform Boolean logic using basic relay instructions. Common input instructions are examine-on (normally open contact) and examine-off (normally closed contact). Input ...

A wiring diagram shows how the electrical control devices are connected by wires and terminals. It also identifies the power supply, input and output devices, relays, timers, switches, sensors ...